Use of fermented black beans combined with rice to develop a nutritious weaning food

Common beans are an important source of energy and nutrients, but have significant amounts of antinutritional factors and a limited digestibility. A nutritious weaning food was developed by combining fermented black beans and rice. Raw beans were coarsely ground, soaked, cooked, fermented with Rhizopus oligosporus for 15, 20, or 25 h, and then homogenized to obtain a supernatant and a precipitate. Raw, cooked, and fermented beans, and the precipitates were chemically characterized and the data statistically analyzed to choose an optimum fermentation time to develop the weaning food product. Ash and mineral contents of the beans decreased after soaking and in the precipitates. Cooking improved protein digestibility and decreased the levels of lectin and trypsin inhibitor. The oligosaccharide content of beans fermented 25 h was lower than in the other treatments. The weaning food product (27% 25 h fermented beans, dry weight/73% cooked rice, dry weight) had an in vitro protein digestibility of 86% and a very low content of oligosaccharides.